In the reaction, h2po4 - + haso4 2 - hpo4 2 - + h2aso4 -, which two species act as acids?

Acids are substances capable of donating hydrogen ion H⁺. On left h2po4 - is acid, because that ion donate one hydogen ion to haso42-, and on the right h2aso4 - is acid, because donate one H⁺ to hpo42 - (when hpo42 - accept one hydrogen ion, he transorms in h2po4-).